Pre-weaned pig mortality, as a result of being crushed by the sow in a farrowing area, accounts for a 6% to 9% loss of all pigs that are farrowed. This loss translates into reduced potential profits for the pork producer.
Conventional farrowing areas are usually equipped with safety zones for the pre-weaned piglets. The safety zones are separated from the farrowing area with a safety bar. The safety bar is just high enough for the pre-weaned pigs to walk underneath. It is usually equipped with a mat and a heat lamp that attracts the pre-wean pigs to the safety zone.
Conventional methods of crush prevention employ the use of additional steel bars in the farrowing area to further restrict the sow, or to slow her descent as she lies down. These methods all attempt to improve the pre-weaned pigs' chances of escaping when the sow is descending upon them. These methods are nominally successful at best. There have been some reported instances where the additional steel bars have caused harm to the sow.
Prior art devices for crush prevention include a portable pig sitter from a Denmark firm which is described in a publication by E. K. Brapps and M. G. Hogberg from the Animal Science Department at Michigan State University. The portable pig sitter, as described in the Brapps and Hogberg article, slips over the side of a farrowing crate on the same side as a heat source which is used to attract the baby pigs. The unit works with an electric eye beaming across the farrowing crate to detect the sow's inclination. When the sow stands the electric eye's beam is broken triggering a fan in the unit. The fan pushes cool air into the farrowing area. This creates an uncomfortable environment under the sow but, in view of the results, does not appear to irritate the piglets enough to afford them protection. The baby pigs purportedly avoid this area and thereby theoretically avoid crushing when the sow lays down. The results of the article indicate that the portable pig sitter does not effectively prevent pre-weaned piglet death. According to the survey the following paragraph describes the results and discussion of the portable pig sitter.
A summary of pig numbers and weights is given in Table 1. There were no significant differences between the control and treatment groups in any of the parameters examined. The use of the portable pig sitter tended to improve slightly the number of pigs alive at 3 days and 21 days. Average 21 day weights also showed some improvements. Death losses from days 1-3 also showed a tendency toward improvement with use of the portable pig sitter. The percentage of death losses due to crushing or overlaying show a reduction in the treatment group (17.6% of losses) over the control group (70.8% of losses). However, the percentage of losses due to starvation, runts or miscellaneous causes were higher in the treatment group (29.4, 35.2 and 17.6%, respectively) over that of the control groups (12.5, 12.5, and 4.2, respectively). This shift of reduced death due to crushing and increased death due to other causes may suggest that the weak pigs were able to avoid being crushed in treatment groups, but later died from other causes whereas the weak or starved pigs in the control group may have continued to stay as close as possible to the sow while she was standing, possibly for warmth or trying to nurse at the next opportunity and these were crushed. Parity significance was examined but no differences were noted.
TABLE 1 ______________________________________ Parameter Treatment Control ______________________________________ No. litters 29 31 No. pigs born 299 332 No. pigs born/litter 289 310 Ave. no. born/litter 10.31 10.71 Ave. no. born alive/litter 9.96 10.00 % stillborn 3.34 3.15 Ave. pig wt. at birth, lb. 3.28 3.15 Per litter No. pigs, day 1 9.96 10.0 No. pigs, day 3 9.69 9.35 No. pigs, day 21 9.20 8.84 Litter wt., day 1, lb. 32.51 31.02 Litter wt., day 3, lb. 37.72 36.26 Litter wt., day 21, lb. 121.08 112.71 Ave. litter wt. gain, lb. 88.57 81.69 Ave. pig wt., day 1, lb. 3.28 3.15 Ave. pig wt., day 3, lb. 3.89 3.87 Ave. pig wt. gain, lb. 9.82 9.60 Death loss, day 1-3 17 (5.68%) 24 (7.74%) Death loss, day 4-21 13 (4.35%) 16 (5.15%) ______________________________________
As a result of the failure of prior art methods there exists a need for a safe and pro-active method that virtually eliminates crushing of pre-weaned piglets resulting by a descending sow. It is also desirable to accomplish this result without restricting access to the sow.
The solution to the aforesaid problem should advantageously also encourage the pre-wean pigs to stay in the safety zone, but more importantly, discourage them from wandering under the sow in the danger zone during the entire time the sow is standing since pre-weaned pigs are creatures of comfort. They are attracted to a comfortable environment and stay away from an uncomfortable environment.
It is therefore the motivation of the invention to provide a safe and effective means of preventing pre-weaned piglet mortality by providing a local irritant to chase the pre-weaned piglets from the danger zone under the sow to the more comfortable environment afforded by the safety zone.